Most of the private mobility nowadays takes place via using a vehicle propelled by an internal combustion engine wherein largely two types of fuels are burnt for driving the vehicle, diesel or gasoline/petrol.
The burning/combustion process of diesel/gasoline involves oxidation of hydrocarbons contained in the diesel/gasoline with oxygen to eventually yield CO2 and H2O. Yet, combustion processes are always inadequate, so that the fuel is only incompletely oxidized, which incomplete combustion process yields toxic substances, such as carbon monoxide (CO) and lower hydrocarbons (HC).
Carbon monoxide is a well known contaminant irreversibly blocking an individual's capability of breathing. Hence, higher concentrations of carbon monoxide in the breathing air will eventually lead to the individual's death. Yet, also lower doses of CO are detrimental to the individual's health by creating depression and heart damage.
Lately it has been found that unburnt hydrocarbons (HC), such as produced by burning fossil fuels in power plants, house heatings, vehicles and in various industrial processes account at least in part of a phenomenon widely known as “respirable particulate matter” or “fine dust”, which terms designate particulate matter smaller than about 10 μm or even smaller than 2.5 μm.
Due to its size such respirable particulate matter may stay in the air for a week or more before settling to the ground by gravitation. Since its production goes along with activities of mankind, the highest levels is found in agglomerates, that is larger cities. In case dislodgement of the particular matter is not effected by wind taking it away to the countryside, it accumulates in the cities' air, even capable of rendering the environment in a haze.
Respirable particulate matter has been recognized as a major threat to human health. The WHO consider airborne particulates a strong carcinogen, since these small particulates have the ability to penetrate into the individuals blood streams unfiltered by the lung or nose barrier, causing permanent DNA mutations, heart attacks, and premature death. A recent study carried out in Europe in 2013 involving about 325.000 people indicated that one the one hand there is no safe level of particulates while on the other hand for each increase of 10 μg/m3 in respirable particulate matter of 10 μm and smaller the lung cancer rate rose by about 20%. Even more, smaller matter with a diameter of less than 2.5 μg was shown to be particularly lethal, increasing the incident of lung cancer by 36% per 10 μg/m3 increase.
In cities the traffic is considered to be a major cause for the production of respirable particulate matter.
In order to reduce toxic emissions from combustion engines the engines have undergone a development for improving utilization of the fuel fed into them while at the same time increasing oxidation efficiency. Further, catalysts have been built in vehicles to further reduce the amount of contaminants contained in the emissions.
Yet, also the fuel composition was the focus for further research to improve its combustion and reducing the production of toxic substances.
GB 950147 A discloses a fuel composition fur improving energy yield containing as the major component hydrocarbons having an octane No. of at least 90 and an octane number-improving amount of an organic-metal-containing anti-knock agent, as well as up to 2 vol.-% by co-anti-knock agents and extenders. As such additives among others iso-propanol and water are mentioned.
U.S. Pat. No. 4,099,930 relates to an energy-saving fuel additive for gasoline and diesel engines which comprises a mixture of picric acid and ferrous sulphate in a solvent of alkyl benzene, isopropyl alcohol, and water. The additive may be injected directly into the combustion engine or added by bulk addition to the fuel container.
JP 7278576 discloses a method of reducing emission of toxic substances from combustion engines by providing an additive for complementing fuel, the additive comprising alcohol(s), such as an ethyl alcohol mixing agent, n-propyl alcohol, iso-propyl alcohol, n-butanol or iso-butanol. Depending on the water content of the alcohol(s) an emulsifier may be used.
Further U.S. Pat. No. 4,992,187 discusses a composition for cleaning combustion engines comprising a composition of selected cyclic compounds, such as N-methyl-2-pyrrolidone, aliphatic amines, such as n-butylamine and water, which are dissolved in hydrocarbons and aliphatic lower alcohols, such as isopropanol.
However, due to the rapidly increasing number of vehicles all around the world there is still an unmet demand to further reduce the amount of toxic emissions from combustion engines.